For the HTML text editor (insert tables) and such to work, you must allow e.g. VB script and javascipt run.
The easiest way is to add http: //yourstore.xx as a 'reliable' site
Internet Explorer >> tools >> internet options >> security >> trusted locations >> Locations >> add and type http: //address.to your store.
Then much more should work as it should. Bl.a. you see 'OK' when you insert a table.